The filament found inside an incandescent light bulb is very delicate. Minute vibrations can cause the filament to weaken and eventually fail. The light bulb manufacture states that in general, 50% of bulbs will fail before they have reached their rated lifespan of 750 hours. The LED tube lighting datasheet indicates an amazing 0% failure rate out of 50 LED lights tested to 1000 hours. Unfortunately, light emitting diode reliability data out to maximum rated life was not available. However, you can clearly see from this information how the home LED lighting design seems much more reliable when compared to the light bulb. In real world applications, LED home lighting reliability is far superior to that of the incandescent light bulb. LED lights are capable of enduring physical shock and vibrations that would literally destroy a standard incandescent light bulb.
A typical incandescent light bulb produces a luminous output of 1350 lumens, according to the manufacturer. This value represents the overall light output from the device. The light emitting diodes within the LED tube lighting we are considering for this example produces a much lower luminous output rating, of only 15 lumens, or 1.1% of light bulb's luminous output. However, in most custom LED lighting designs, LEDs exist in arrays containing numerous LED lights. In this example, ninety LEDs will provide a luminous output equal to one incandescent light bulb. Each light bulb sales for $0.48 when purchased in value packs containing four bulbs. We can use this information to calculate for cost efficiency by dividing the luminous output by cost of the bulb, and get 2813 lumens per dollar. Consider our cost per light emitting diode is equal to $1.00. When we divide to calculate for LED cost efficiency, we get 15 lumens per dollar. According to these preliminary calculations, $90.00 worth of LEDs is required to achieve the same amount of light produced by a $0.48 light bulb. It is important to account for additional costs associated with real world LED tube lighting applications. For simplicity purposes, this article does not factor in the additional costs induced by assembly labor, power supplies, external components, heat sinks, and circuit boards. With this said, it seems apparent why most household lighting applications do not incorporate LED technologies. However, do not draw any conclusions until after considering the following additional factors.
Many people tend to believe that an home LED lighting designs will provide sufficient lighting for 100,000 hours and beyond. In most cases, this is simply not true. As the LED light ages, it will continuously loose efficiency and become noticeably dimmer. However, the custom LED home lighting still offers a much longer overall lifespan when compared with the incandescent light bulb. The light bulb's lifespan rating is 750-hours (about one month of continuous operation) according to the manufacturer. Note that the industry standard for determining LED lifespan is the point at which the LED lights have reached 50% of their luminous output. The home LED lighting can operate for approximately 40,000 hours (4.5 years of continuous operation) before reaching 50% of its initial luminous output. By the time the light bulb has reached the end of its life expectancy, the LED will continue to provide nearly 100% of its original luminous output. It is apparent that the LED can survive more than 50 times longer than a typical incandescent light bulb.
Our incandescent bulb's power rating is 100 watts. To calculate for energy efficiency we divide the luminous output 1350 lumens, by this power rating and get 13.5 lumens per watt. Since one watt only produces a luminous output equal to 13.5 lumens, we can conclude that a large portion of wasted energy escapes in the form of heat. Our LED lights power rating is 525mW (0.525 watt). This value is equal to test condition current (150mA) multiplied by the forward voltage drop of 3.5 volts. When we divide to calculate for energy efficiency, we get 28.6 lumens per watt. As you can see, the LED light will produce more than twice as much light, per watt of power. Therefore, the LED is about 2.1 times more energy efficient.
We have already concluded that the LED light is about 2.1 times more energy efficient than our incandescent light bulb. The next step is to calculate for operating costs based on amounts of electricity consumed during operation. To do so, we need to know how much the utility company charges for electricity per kilowatt-hour. Then simply divide by one-thousand and multiply by the device's power consumption. Finally, multiply this by total hours of use. If the utility company charges $0.085 per kilowatt-hour, the light bulb will cost $74.46 to operate, after one year of continuous use. We have already determined that 90 LEDs will provide a luminous output equal to a single 100-watt light bulb. Each LED is rated at 525mW so 90 LEDs is equal to 47.25 watts. Using this information, we can compute for LED operating cost, and discover that ninety LEDs will only cost $35.18 to operate, after one year of continuous use. By utilizing LEDs, overall utility-bill savings would equal $39.28 per year, or about $0.11 a day. For simplicity purposes, we have excluded power calculations associated with external components required to drive the LED circuitry. In a real world application, overall the LED circuit's power consumption is slightly higher.
We have concluded that our LED lights have a lifespan 53 times longer than an incandescent light bulb. Additionally, the LED light is 2.1 times more energy efficient and therefore costs about half as much to operate. Consider the overall costs of purchasing and operating the LED and light bulb for a continuous four-year period. You would need to purchase 47 light bulbs considering the 750-hour lifespan. At $0.48 per bulb, overall light bulb material costs add up to $22.56. Over the four-year period, the cost of electricity to operate the light bulbs will total $297.84. The grand total for our light bulb including materials and operating costs is equal to $320.40. If utilizing LEDs, you would need to purchase 90 LEDs, on one occasion. At $1.00 per LED, overall LED material costs equal about $90.00. Over the four-year period, the cost of electricity to operate the LEDs will total $140.72. The grand total for our LEDs including materials and operating costs is equal to $230.72. By switching to LEDs, your overall savings is $67.12 per four-year period. Although this may not seem like much at first, keep in mind this calculation was only for a single lighting fixture. Imagine the accumulative savings over a 10-year period in a house equipped entirely with LED lighting!
Unfortunately, in most cases today, LED home lighting lacks in terms of cost efficiency when compared with traditional incessant lighting systems. When you account for other variables, LED cost efficiency suffers dramatically. Our example offers readers with the basic concepts involved with comparing home LED lighting to traditional methods of home illumination, such as the incandescent light bulb. This article does not provide an exact formula that accounts for all variables, many of which can dramatically alter material and operating costs. Unlike the incandescent light bulb, LED home lighting always require additional circuitry to operate. This LED circuitry usually includes electronic components, heat sinks, a circuit board, and some form of power supply. Custom LED lighting systems are generally more complex, and require assembly on numerous levels. All of the costs associated with these items need to be factored into cost efficiency calculations. Lumen maintenance is another important factor worthy of careful consideration. Dimming LEDs present a complex variable in all power and cost related efficiency calculations. Therefore, it is necessary to perform all calculations based on the diminishing luminous output as the LED ages. Together, these factors present some of the greatest challenges engineers in the LED lighting industry must work to overcome.